In order to measure physical change amounts, such as force, pressure, torque, velocity, acceleration, impact force, weight/mass, degree of vacuum, turning force, vibration, and noise, there has heretofore been proposed and put to practical use a physical quantity sensor device that uses a strain-sensitive resistor having characteristics, i.e., strain-sensitive characteristics, varying the electric resistance depending on a change in the quantity of strain. The strain-sensitive resistor that has been known comprises a matrix made of glass, i.e., a glass matrix, in which electrically conductive particles are dispersed.
In order to provide a physical quantity sensor device capable of highly sensitive measuring of a physical quantity maintaining high precision, for example, JP-A-2005-172793 discloses a physical quantity sensor device comprising a pressure-sensitive body which varies electric characteristics upon the application of stress, and electric insulators formed on each of the two opposing surfaces of the pressure-sensitive body integrally therewith, wherein the pressure-sensitive body comprises a matrix of glass in which electrically conductive particles are dispersed.
In order to provide a strain detector device having a strain resistive device that forms a highly stable electrically conductive path while suppressing fluctuation in the resistance when stress is exerted or removed, further, JP-A-2003-247898 discloses a strain detector device of which the strain resistive device is obtained by firing a resistor paste which chiefly comprises an electrically conductive component-containing glass containing electrically conductive particles in the glass frits.
In order to provide a physical quantity sensor elemental structure which facilitates electric connection to an external unit and makes it possible to form an electric connection portion that is free from being affected by the application of a large physical quantity, JP-A-2005-189106 discloses a physical quantity sensor elemental structure in which an insulator and a detector unit are laminated in a direction in which a physical quantity is applied, and the detector unit has an electric connection surface on the main surface thereof on the side that is closely adhered to the insulator, the electric connection surface being exposed without the insulator.
However, the above pressure-sensitive bodies have a gauge factor GF), which is the sensitivity index of not more than about 30, exhibiting good strain-sensitive characteristics as compared to the case of using a metal foil gauge that has a GF of not more than about 2, but are inferior to use of a silicon semiconductor having a FG of not larger than about 200. Therefore, in order to accurately detect the physical quantity without using a strain-causing body, the pressure-sensitive bodies, such as the above resistor bodies, lack sensitivity. In addition, the glass matrix that contains lead which places a burden on the environment.
In order to provide a physical quantity sensor device capable of attaining both the formation of a strain-sensitive resistor using a lead-free glass matrix and the expression of strain-sensitive characteristics at a level sufficient for practical use, JP-A-2005-189106 discloses a physical quantity sensor device of which the strain-sensitive resistor is obtained by dispersing electrically conductive particles in the matrix which does not contain lead, but contains bismuth. However, the physical quantity sensor device is still far from having highly sensitive strain-sensitive characteristics.
In order to provide a paste for forming a thick-film resistor that is used as a resistive device for hybrid ICs and thick-film chips, featuring low noise and excellent withstand voltage, and a treated glass frit for the paste, JP-A-6-028916 discloses a paste for forming a thick-film resistor, comprising a treated glass frit, a lead borosilicate glass frit and an organic vehicle, wherein the treated glass frit containing at least one of rhenium oxide, ruthenium oxide, iridium oxide, rhodium oxide, rhenium type pyrochlore, ruthenium type pyrochlore and iridium type pyrochlore in the form of clusters with a diameter of not more than 10 nm, penetrating and dispersed in the lead borosilicate glass particles.
However, the thick-film resistor used as a resistive device for hybrid ICs and thick-film chips is a material that gives importance to stabilizing the resistance and is, therefore, designed to minimize a change in the resistance caused by strain, i.e., caused by thermal stress due to a difference in the thermal expansion from that of the substrate, and thus cannot be used as the physical quantity sensor device.
In addition, concerning laser deposition, JP-A-2006-326477 proposes a method of manufacturing a catalyst for purifying exhaust gas, characterized by carrying a noble metal and a NOx-occluding material on a carrier oxide relying on a laser abrasion method, by using a target that contains a noble metal source, a NOx-occluding material source and a carrier oxide source, in an attempt to carry the NOx-occluding material in a more fine state, and carry the noble metal and the NOx-occluding material in an alternately and highly dispersed state.